The proposed constitutional amendment passed the House earlier this month. It was adopted by the Senate Transportation and Infrastructure Committee on Thursday with a 6-1 vote.

If passed by the full Senate, the measure would head to the November ballot for voter approval. The tax is estimated to generate $800 million annually and $8 billion over its 10-year lifespan.

The lone "no" vote on the Senate panel was Republican Sen. John Lamping, who led the fight against similar legislation last year. He says Republicans are sending a mixed message by raising sales taxes, while also passing an income tax cut this year.

Supporters say the tax is necessary for Missouri to maintain its highway system.